Water first appear in level 7. When Slime enters water and has not absorbed any slime, the main character will rise to the surface of the water and be mostly submerged in it. Jumping in water will cause Slime to go deeper upon landing in water but then Slime will return to the surface. If the player makes Slime move, Slime will begin to swim. Jumping out of water onto dry land will cause some water droplet to be flung out.

If Slime becomes bigger by absorbing slime bits, Slime will sink in the water and can get out again by pressing the jump button to go higher. Slime will be constantly pulled down to the bottom of the floor unless the player makes Slime jump. Spikes and anglerfish are sometimes present in water.